Absorption spectra and photochemical rearrangement of octatetraene and decapentaene radical cations in solid argon

Abstract

Parent radical cations of octatetraene and decapentaene have been prepared and trapped in solid argon using matrix photoionization methods with both cyclic and acyclic precursors. Visible absorption spectra are assigned to the all- trans cation isomer and several structures with increasing numbers of cis configurations. Irradiation into these bands with argon and krypton ion laser lines caused reversible rearrangements among several of the configurations for octatetraene and decapentaene cations. The cold matrix provides an excellent medium for studying molecular cation rearrangements where one structure can absorb light and other structures formed can be relaxed by the matrix before dissociation